MNSR 7 - Muscular System: Anatomical Muscles and Muscle Physiology Flashcards
(52 cards)
What are muscles?
Aggregations of cells which convert chemical energy (ATP) into mechanical energy (movement)
Highly adapted cells allowing for force-generation (i.e. contraction)
Specialized adaptations of cellular components (e.g. sarcoplasmic reticulum and contractile proteins)
What are the three muscle types?
Skeletal muscle
Attached to bones which form levers- used for bodily movement
Cardiac muscle
Walls of the myocardium - used to pump blood through circulatory system
Smooth muscle
Organs - lines gut and blood vessels - controls diameter of these tubes and in gut helps to propel the digested food
What is the structure of the smooth muscle?
Lines the digestive tract, bronchus and blood vessels
* Involuntary muscle i.e. not under direct nervous control
* Lacks the striations of skeletal and cardiac muscle tissue
*1 nucleus per smooth muscle cell
*High endurance muscle
What is the function of smooth muscle?
Sustained contractions (e.g. small and large intestine)
Where is cardiac muscle found?
Found only in the walls of the heart
What is the structure of cardiac muscle?
- Unevenly striated
(so similar to skeletal muscle in appearance) - Alternating light and dark bands (striations) as seen when examined with a microscope
- High endurance (high number of mitochondria); contracts throughout the lifespan
- (1- 2 nuclei per cardiac cell/myocyte (centrally placed)
- Innervated by the pacemaker
fused-together cylindrical cells
At border between one cardiac cell and the next are “Intercalated discs”which support synchronized contraction of cardiac tissue. These discs contain: desmosomes and gap junctions.
The fused cardiac cells contract as a unit owing to signals at gap junctions between them
What are the functions of cardiac muscles?
- Contraction is involuntary (like smooth muscle)
- Contraction and relaxation of the heart is not consciously controlled
- Contraction of the heart is initiated by a node of tissue called the “pacemaker”
What is the structure of a skeletal muscle?
- So named because most skeletal muscles move bones
- Called striped or striated due to appearance under light microscope
- Long cylindrical cells
- Many nuclei per cell (‘multinucleated’)
What is the function of the skeletal muscle?
- Locomotion, posture; head, limb movements
- Voluntary muscle i.e. under direct nervous control. e.g. biceps muscle
often reflex-activated - Endurance capacity depends on number of mitochondria.
How is the skeletal muscle often described as?
Often described as being of ‘low endurance’ compared to other muscle types.
Each muscle is composed of bundles of…
fascicles
Each fascicle is composed of many…
muscle fibres
In most anatomical muscles the fibres extend the…
entire length of the muscle
Each fibre is composed of _______________ which contain the contractile apparatus – the ____________
smaller myofibrils, sarcomere
Muscles have extensive vascular systems that…
1) Supply large amounts of oxygen
2) Supply nutrients
3) Carry away wastes
Skeletal muscles are voluntary muscles, controlled by…
nerves of the central nervous system (brain and spinal cord)
The connective tissue components include…
Epimysium
* The outermost layer
Perimysium
* Surrounds numerous bundles of fascicles
* Separates 10-100 muscle fibers into bundles called fascicles
Endomysium
* Separates individual muscle fibers from one another
Tendon
* Cord that attach a muscle to a bone
How would you describe muscles?
Tissue with the ability to contract
How would you describe tendons?
Tough band of fibrous connective tissue that connects muscle to bone
How would you explain ligaments?
Attaches bone to bone
One attachment is fixed and called the…
origin
The other called the _________________ is drawn towards the origin.
insertion
Muscles can only…
contract and never push
Arranged in
antagonistic pairs
